It also appears your walls are gray. You can keep gray walls with a gray sectional if you add a yellow accent color or a blue accent or a coral accent.

Jennifer Brouwer Design Inc. · More Info

Contemporary Family Room · More Info

Contemporary Living Room · More Info

In this photo, gray sectional with greige walls ( beige/gray mix):

Hilltop House | Grand Vista Subdivision · More Info

Suburban Contemporary Family Room · More Info

You can absolutely do that with a gray sectional. That is the joy of such a versatile 'color'. Let me see what I can find as visuals...

Here are two- will let you see how they work together:

I love the color of your door and I would leave it! It adds a pop of color, especially against the white trim and gray walls.

Some delightful Ikat navy and white pillows at Etsy (similar to the pillows in last photo)

https://www.etsy.com/search?ref=gslsb&q=navy%20blue%20ikat%20pillow

Or go with plain pillows and add a fun ottoman :

http://www.target.com/p/surya-furniture-geometric-ottoman-olive-gold/-/A-17132010?ref=tgt_adv_XSP10002&AFID=polyvore_df&LNM=17132010&CPNG=Furniture&LID=30pdf&ci_src=426179448&ci_sku=17132010&gclid=COjbwuv4yMsCFY6tNwodyggEqg&gclsrc=ds

or a navy ottoman :

http://www.overstock.com/Home-Garden/Renate-Navy-Linen-Coffee-Table-Ottoman/8840576/product.html?refccid=GBLHKFNYCRMKOXSCV7AGOO2TY4&searchidx=65

and/or gold drapes:

http://www.overstock.com/Home-Garden/Gold-Geometric-Curtain-Panel/11177250/product.html?refccid=WFDOFBXXZG7I6B2LCEHSBMJ25U&searchidx=9

or navy drapes:

http://www.overstock.com/Home-Garden/Aurora-Home-Grommet-Top-Thermal-Insulated-96-inch-Blackout-Curtain-Panel-Pair/4359824/product.html?recset=1c06f008-38c5-45e9-b310-28914addaea8&refccid=AEEE64W6HE42S2CPEQVSINLZ3A&recalg=806&recidx=3

If you go with the navy and gold, yes the door needs to be painted. White is safe.

Some art work ideas:

http://www.art.com/products/p8443233113-sa-i5297062/megan-aroon-duncanson-renaissance.htm?sOrig=CAT&sOrigID=206575&dimVals=206575-207272&ui=50571D48A7FC41E599582376CE458484

http://www.art.com/products/p10901408414-sa-i6108031/ledent-blue-cornflowers-756.htm?sOrig=CAT&sOrigID=206575&dimVals=206575-207272&ui=50571D48A7FC41E599582376CE458484

http://www.art.com/products/p14920885058-sa-i6819599/violet-leclaire-moody-indigo.htm?sOrig=CAT&sOrigID=206575&dimVals=206575-207272&ui=50571D48A7FC41E599582376CE458484

http://www.art.com/products/p12896320-sa-i2184937/diana-mayfield-doorway-in-old-venetian-quarter-hania-crete-greece.htm?sOrig=CAT&sOrigID=0&dimVals=207226-207272&ui=50571D48A7FC41E599582376CE458484&SSK=Posters&PODConfigID=4990619

http://www.art.com/products/p13943791-sa-i2748696/claude-monet-sunflowers.htm?sOrig=CAT&sOrigID=0&dimVals=207226-207272&ui=50571D48A7FC41E599582376CE458484&SSK=Posters&PODConfigID=8880730